#include <iostream>
#include <vector>
using namespace std;

class Solution
{
public:
    static int peakIndexInMountainArray(vector<int>& arr)
    {
        int left = 0, right = arr.size()-1;

        while(left < right)
        {
            int mid = left+(right-left+1)/2;
            if(arr[mid] >= arr[mid-1])
            {
                left = mid;
            }
            else
                right = mid-1;
        }
        return left;
    }
};
